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Full text of "Texas fever"

UNIVERSITY OF CALIFORNIA Agricultural Experiment Station 

COLLEGE OF AGRICULTURE E, W. HILGARD, DIRECTOR 

BERKELEY, CALIFORNIA 



CIRCULAR No. 1 

(May, 1903.) 



TEXAS FEVER 

By ARCHIBALD R. WARD, 

Veterinarian and Bacteriologist. 



Synonyms.— Other names by which the disease is known are: South- 
ern Cattle Fever, Bloody Murrain, Splenic Fever, Red Water, Tick 
Fever, etc. 

Symptoms. — In the acute (severe) type of the disease a fever is noticed, 
and results in dullness, lack of appetite, and constipation. The pulse 
and respiration both increase in rapidity. The muzzle and mouth may 
be dry and the head usually droops. Affected animals prefer to stand 
in water. Some animals exhibit extreme dullness, but others may be 
delirious and unusually active. The one most characteristic symptom 
is the voiding of dark, blood-colored urine by animals in the advanced 
stages of the disease. When any considerable number of animals are 
affected, some of them are quite sure to exhibit this symptom, which is 
of great value in recognizing Texas fever to those unfamiliar with it. 
During the progress of the disease the victims grow steadily weaker, 
appearing pale and bloodless. The attack may run a week, and result 
in death or slow recovery, frequently with relapse. Deaths frequently 
occur within a few days after the animal is noticed to be ailing. In 
some animals, not very susceptible to the disease, it assumes a mild 
type, manifested by dullness, lack of appetite, and costiveness. Texas 
fever is exclusively a cattle disease and is active during hot weather. 

Post-mortem Appearances. — The liver and spleen (milt) are the organs 
most usually altered in appearance. The liver is enlarged, and the 
organ is not as tough as in health. The color is usually brownish yel- 
low, due to bile dammed up in the biliary vessels. The gall bladder is 
distended with thick, tarry bile. The spleen is enlarged, and if cut open 
the contents will flow out slowly like thin jam. The blood is noticeably 
thin and pale. There occur other changes not readily recognized by 
persons unfamiliar with the study of diseases. 

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Cause of the Disease. — The above-mentioned changes in the body, and 
others that can be detected only with the microscope, are caused by 
minute animal parasites in the blood. The red-blood corpuscles are 
infested with the parasites, which bring about the destruction of the 
corpuscles and prevent the blood from performing its natural function 
in the body. The blood-colored urine, in severe cases, is an evidence of 
the breaking down of these corpuscles, resulting in the discharge, through 
the urine, of the red coloring matter of the blood, which is normally 
carried by the corpuscles. The microscopic examination of the blood of 
an affected animal will reveal the parasites imbedded in the corpuscles, 
but visible only as small round or pear-shaped dots even with the best 
microscope. The parasites are always present in the blood of an 
animal sick with Texas fever, but under certain conditions may be 
present in limited numbers without causing sickness. 

How Texas Fever is Spread. — For all practical purposes we may con- 
sider the disease as being communicated from one animal to another by 
means of the cattle tick (Boophilus annulatus), and by no other species 
of tick. The disease is not known to be spread by any other means. 
The habits and life history of this tick are intricately involved in the 
spread of the disease and furnish explanation for all of the principal 
peculiarities observed in the spread of Texas fever. 

The cattle tick lives a parasitic life, usually in some unexposed place, 
upon the hide of cattle, sucking the blood. If the blood of the host 
contains the Texas-fever parasites, as is practically always the case, the 
ticks become infested with them. When the female ticks reach maturity 
(one quarter to half an inch long) they loosen their firm hold upon the 
skin and drop to the ground. Each female may lay from 1,200 to 3,000 
eggs, after which she dies. The eggs hatch in about twenty days, but 
the hatching may be retarded or prevented by unfavorable conditions, 
chief among which is brilliant sunlight. 

The young ticks, when not clustered together, are readily killed by 
water; and a temperature of 15° Fahr. for twenty-four hours will kill 
them. They are endowed with an instinct to climb upon cattle within a 
few days after hatching, if opportunity occur; but in the absence of 
cattle (or horses) they will starve in time. If the female tick has been 
nourished with blood containing the Texas-fever parasites, all the young 
ticks hatching from her eggs will contain the Texas-fever parasites. 
When such a young tick gains access to an animal and sucks blood, the 
Texas-fever parasites are imparted to the blood of the animal upon 
which the young tick is living. If the animal infested by the young 
ticks is susceptible to Texas fever, the disease will appear in about ten 
days after the ticks get on it. The ticks mate shortly after infesting an 
animal, and nowhere else; after which they become firmly fixed to 



their host without leaving the animal until ready to drop off, as already- 
described. 

Since cold weather kills ticks, their eggs and young, the species in 
question is limited to mild climates. During the summer, ticks may be 
introduced into the northern parts of the United States and occasion 
immense damage, but the rigorous winter climate exterminates the 
ticks and consequently the disease. 

There are several species of ticks that occasionally are found on the 
hides of cattle or in their ears; but only one kind, popularly known as 
the "fever tick/' is concerned with the spread of Texas fever. This 
species practically always contains the Texas-fever infection, unless it 
has been parasitic upon the horse, which occurs sometimes. 

The Seventeenth Annual Report of the Bureau of Animal Industry 
at Washington contains a description of the cattle ticks of the United 
States, together with colored illustrations. The book can in most cases 
be obtained from Members of Congress, or by purchase from the Super- 
intendent of Documents, Union Building, Washington, D. C. The 
Veterinarian of the Agricultural Experiment Station at Berkeley will 
be glad to identify specimens of ticks sent him by mail. 

Why Ticks May Infest Cattle Without Causing Texas Fever. — Among 
a herd of cattle infested with the Texas-fever ticks the calves become 
infested with ticks when very young, and suffer a mild attack of Texas 
fever. Calves withstand the disease readily and seldom die. As a 
result of this attack they grow up practically immune to the disease, 
and are usually able to tolerate the presence of numerous ticks upon 
their bodies. This immunity is not absolute, for animals excessively 
covered with ticks may again contract the disease under especially 
unfavorable conditions, with fatal results. The fact that animals may 
bear ticks without necessarily contracting Texas fever has induced some 
people to refuse to believe that ticks are dangerous under any conditions. 
Such a view of the matter is indefensible. 

Conditions Under Which Ticks Are Dangerous. — All cattle other than 
young calves are liable to contract a serious type of Texas fever when 
first bitten by infectious ticks. The disease is therefore a menace to all 
cattle raised in regions where cattle ticks do not exist. Whenever tick- 
infested cattle come in contact with non-immune, i. e., tick-free cattle, 
some of the latter will contract the disease after ten days or more- 
Worse yet, the disease may be contracted by susceptible animals by 
feeding upon a range formerly occupied by tick-infested cattle, for young 
ticks may be present waiting to attach themselves to the cattle. Losses 
will occur from Texas fever when tick-infested southern cattle are taken 
north among non-immunes, just as soon as a female tick drops off to 



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the ground and the second generation gets upon the northern cattle. 
Northern-bred animals will contract the disease when taken among 
ticks. An animal may be bred in the south in close proximity to ticks 
and yet escape them until it reaches adult age, when it will suffer from 
the disease if infested by ticks. 

The Federal Quarantine Line. — To restrict the movement of cattle 
from tick-infested regions to tick-free regions, the United States Depart- 
ment of Agriculture has established a quarantine line across the con- 
tinent from the southern boundary of Virginia to the Bay of Monterey? 
in California. In California the Federal quarantine line lies as follows: 
" Beginning on the Pacific Coast where the northern boundary line of 
" Monterey County connects with the Pacific Ocean ; thence easterly 
" and southerly along the northern and eastern boundary line of Mon- 
" terey County to its junction with the western boundary line of Fresno 
" County; thence northerly along the western boundary line of Fresno 
" County to the western corner thereof ; thence northerly, easterly, and 
" southerly along the western, northern, and eastern boundary line of 
" Merced County to the southeastern corner thereof ; thence north- 
" easterly along the northern boundary line of Madera County to the 
u northeast corner thereof ; thence southerly and easterly along the 
" eastern boundary lines of Madera, Fresno, and Tulare counties to the 
" southeast corner of Tulare County ; thence easterly along the southern 
u boundary line of Inyo County to its intersection with the eastern 
" boundary line of the State of California." 

The line marks the southern boundary of the region free from ticks, 
and is moved from time to time as the ticks are exterminated from 
pieces of territory contiguous to the line on the south, or as the ticks 
encroach upon the territory to the north of the line. Under the regu- 
lations of the United States Department of Agriculture and the laws 
of California the movement of cattle across the line is restricted so 
as to minimize the losses from Texas fever. Tick-infested cattle des- 
tined to a slaughter-house may be taken across the line at any time, but 
others from certain districts may be transported across the line only 
when inspected by State or county inspectors and pronounced free from 
ticks. There are many districts south of the quarantine line in Cali- 
fornia that are free from ticks, and consequently cattle therein should 
be and are allowed to be taken north after inspection. For more exact 
information concerning the regulations affecting the movement of cattle 
address inquiry to the State Veterinarian, Sacramento, California. 

Inoculating for Texas Fever. — Moving susceptible animals into tick- 
infested regions is always attended with risk. Calves taken in during 
the winter have the best chance to escape. At that time the ticks are 
not numerous, and the age of the calves and the climatic conditions of 



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winter favor their recovery when infested by the ticks. But there are 
numerous occasions when it would be desirable to move susceptible 
adult animals on to tick-infested ranges, and in consequence an opera- 
tion known as inoculation or vaccination has been devised. The process 
consists in transferring to the susceptible animal some blood from a tick- 
infested animal, and thereby producing an attack of the disease usually 
mild and not fatal ; that is, the animal is artificially immunized against 
Texas fever. The operation is sometimes designated vaccination. It 
is most safely performed in California during the winter months and at 
a time when feed is good, as these conditions are conducive to the recovery 
of the animal from the inoculation attack of the fever. 

The existing methods of inoculation for Texas fever have hardly been 
simplified enough to justify recommending their use by men unskilled 
in the work. Inoculation, unless performed by a man thoroughly 
familiar with the disease, is liable to lead to disastrous results. The 
writer believes that he is ministering to the best interests of stockmen 
in advising the employment of a competent veterinary surgeon to do 
the work. This so-called vaccination is not a remedy, and should not 
be practiced upon sick animals. 

Recognition of Texas Fever. — The disease is not difficult to recognize. 
Practically always the history of the outbreak shows that there has been 
the movement of one or more animals in such a way as to result in the 
infestation of non-immune animals by ticks. One must not expect to 
succeed in finding the ticks upon a freshly-infested animal, for they are 
so small as to practically elude discovery. The fact that they could not 
find ticks on the affected animals has led many stock owners to errone- 
ously conclude that their cattle were not suffering from Texas fever. 
Further facts to assist in recognition are fever, gradually increasing 
weakness, and voiding of red-colored urine. Conclusions may be further 
strengthened by examining the liver and spleen after death. Hogs are 
not injured by eating the flesh of cattle dead of Texas fever. 

Treatment of Texas Fever. — Removal of the animals from the infested 
range is essential. The removal of the ticks is desirable, but attended 
with considerable difficulty. With large numbers of range stock this is 
accomplished with more or less completeness by dipping the animals in 
a large vat constructed for the purpose and containing some substance 
harmful to the ticks. A grade of oil known as extra dynamo oil has been 
used, floating in a layer several inches deep on the vat of water. One 
per cent of sulfur has been found to improve its action. Fish oil has 
been used successfully in the same manner in a vat or has been applied 
to tame cattle by hand, with satisfactory results. Cooper Curtice sug- 
gests the following mixture : Kerosene and lard, of each, one gallon ; 
sulfur, one pound, and two pounds of pine tar. Melt the lard, to which 



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should be added the tar and sulfur, all of which is brought to the boil- 
ing point. Cool, and stir in the kerosene. This is to be rubbed over 
the animal daily. Such treatment is only applicable to small numbers 
of domesticated animals. 

Cottonseed oil has been used with success on small numbers of cattle- 
Practically all of the numerous dips that have been devised are unsatis- 
factory in some respects. Some injure the health of the animals, 
especially the eyes; others are inefficient in not killing the ticks with 
one dipping. Oil dips, on the whole, are the most satisfactory of all 
the various dips that have been tested for killing ticks. But the 
operation of dipping, however necessary, sometimes tends to aggravate 
the disease. 

Medical treatment is practicable only when it is desired to save some 
particularly valuable animal. A dose of a pound and a half of Epsom 
salts, together with an ounce of ginger, should be given in a drench. 
Dr. J. C. Robert, of the Mississippi Agricultural Experiment Station, 
advises the following treatment : "Administer bisulfate of quinine in 
"from 60 to 120 grain doses, dissolved in one half pint of water. Give 
" the quinine every two to four hours as long as the temperature of the 
"animal remains above 103° Fahr , then gradually decrease the dose. 
" Should the animal grow weak, it should have combined with the quinine 
" from one to three ounces of alcohol or twice that amount of whisky. 
" When improvement commences the administration of an iron tonic 
" will be found of value. We may prepare such a tonic by the use of 
" powdered sulfate of iron 2 parts, powdered nux vomica 1 part, powdered 
"gentian root 1 part, sulfate of soda 2 parts, and common salt 4 parts ; 
" mix these ingredients and give to a grown animal from one to one and 
"one half heaping tablespoonfuls in feed twice daily. Too much pains 
" can not be taken with nursing a case of Texas fever. The high fever 
" incident to the disease rapidly exhausts the animal's strength, and 
"unless the proper nourishment and care is given death may result 
" before we look for it. Give tempting, nutritious, laxative diet and pure 
"drinking water. If the animal refuses to eat, drench every four hours 
" with one quart of sweet milk in which has been beaten four or six 
" raw eggs." 

The Eradication of Texas Fever. — Since practically the tick alone 
spreads the fever, the extermination of the tick from a district frees that 
place from Texas fever. Removal of cattle from the infested range and 
persistent dipping will clean the cattle of ticks. Exclusion of cattle 
from a piece of infested territory for two winters and the intervening 
summer will free the place from ticks, which starve out for lack of a 
host. These measures are chiefly relied upon along the quarantine line 



to exterminate the tick, resulting in the removal of the line to a point 
south of the freshly-cleaned territory. The great difficulty in accom- 
plishing the work lies in the difficulty in persuading all stock owners to 
see the desirability and necessity of eradicating the tick, and in inducing 
them to work together.